Marcus Tullius Cicero (106 BC) is widely touted as one of the greatest thinkers of Ancient Rome, described by admiring scholars as "perhaps the most civilised man who ever lived" [1]. Due to his proficiency in Greek, Cicero was able to translate many Greek literary works into Latin and thus aid the spread of Greek philosophy and thought through Rome.

Cicero was a prominent and brilliant lawyer, orator and statesman, rising to the position of consul in 63 BCE. Politically, Cicero was opposed to the formation of the Empire and advocated a republican form of government. This placed him offside with powerful figures in the tumolt preceding the civil war, as he was critical of the rule of both Julius Caesar and Mark Antony, and refused to join Caesar's first triumvirate with Crassus and Pompey. Following the victories of Mark Antony Cicero was a hunted man and was assassinated in 43 BCE.

Summarised from Robin Lane Fox, The Classical World: An Epic History of Greece and Rome (2005), 366-376.

Cicero urged the Romans to adopt Stoic ethical teachings (Stoicism began in Greece).
Key points to Stoicism: (1) No one is outside the real community, the human community -- they developed the idea of 'citizens of the world.' (2) Humans live in a series of concentric circles, first encircling the self, then the family, then the extended family, then close personal friends, then neighbors, then city dwellers, then country men and then humanity as a whole. (3) And our obligation/duty is to give each of these circles their due respect. (4) Human beings are meant to follow natural law, which arises from reason.
  1. Baldson, J.P.V.D., in Dorey, T.A. (ed), Cicero (1965), p.205